There is an increasing need for gas sensors which can distinguish extremely low levels of particular gaseous species in the presence of large concentrations of interfering species.
Several fiber optic and integrated optical transducers have been proposed as chemical sensors. Typically, such proposed sensors have been based on a change in the effective refractive index of a guided light mode due to a change in refractive index and/or a change in the thickness of a sensing overlayer. Many such sensors have one or more deficiencies in sensitivity, selectivity, or response time. Thus there is still a need for highly sensitive and selective gas sensors which operate in near real time.
Therefore, it is an object of this invention to provide a method and apparatus for rapid detection of low levels of selected chemical species.
It is another object of this invention to provide a method for sensing chemicals by analysis of changes in the refractive index of a thin film of host reagent on a waveguide caused by the formation of guest-host inclusion complexes in the thin film.
It is yet another object of this invention to provide a method and apparatus for detecting volatile and semi-volatile organic compounds.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. The claims appended hereto are intended to cover all changes and modifications within the spirit and scope thereof.